The present invention relates to particle blasting equipment and methods, and more particularly to particle blasting equipment and methods for monitoring media flow, nozzle wear, and nozzle blockage.
Particle blasting equipment is used in a variety of applications for a variety of purposes. In particular, such equipment is used to compressively peen metal parts to improve fatigue and stress characteristics of the parts. Particle blasting equipment is also used to blast objects to remove surface irregularities, dirt and the like.
Typically, particle blasting equipment includes a source of compressed air, structure for conveying the compressed air from the source, structure for introducing the particle blasting media into the airstream, and a nozzle for directing the airstream, carrying the blasting media, against a desired article. One problem that has plagued the industry is that often either excessive or insufficient media is directed onto the articles being blasted, resulting in improper blasting of the articles.
A particle blasting nozzle typically includes a restricted opening to focus or direct the media passing therethrough. As the blasting media passes through the nozzle, the restricted opening is worn away and enlarged. Ultimately, the opening is so enlarged that the media stream is not properly focused. Consequently, nozzle wear must be monitored to determine the appropriate time to replace the worn nozzle with one having a properly dimensioned opening.
The nozzle may also become blocked due to excessive media accumulation within the nozzle. When such blockage occurs, blasting is interrupted until appropriate corrective action is taken. Accordingly, the nozzle must also be monitored for blockage as well as excessive wear.
Media flow in prior blasting equipment is monitored by either viewing the media discharged from the nozzle or observing the amount of media expanded during a given time. However, a visual observation of the media passing out of the nozzle does not provide an accurate measurement of the media flow. Monitoring the media expanded over a given quantum of time provides only an average media flow and does not indicate periods of shorter duration when the media flow falls above or below acceptable levels.
Typically, nozzle wear in prior equipment is inspected only after the airstream is interrupted. The restricted opening is examined either visually or using a measuring gauge. Such an examination is time consuming, requiring equipment shutdown, and must be performed repeatedly. Nozzle monitoring problems are further complicated when the nozzle is located within a shroud or other protective equipment.